1. Field of the Invention
The invention relates to new polycarbon sulphide derivatives, to the preparation thereof and to the application thereof, particularly in electrochemistry.
2. Discussion of Background
There have already been described in the review "Carbon", Vol. 19 page 175 et seq (1981), superficial complexes of carbon and sulphur which provide the possibility of establishing carbon-sulphur bonds at the surface of the carbon, thus forming superficial carbon-sulphur complexes.
However, given the high temperatures involved in their preparation, of the order of 500.degree. C. to 800.degree. C., the carbon chains are branched. This reduces the number of sites available to be sulphuretted. In this connection, examination of these compounds confirms that their sulphur content is a maximum of 40% this is considerably less than the theoretical value, resulting in a reduction in the capacity of these compounds per unit mass. Also, the high temperatures involved lead to excessive energy consumption.
Moreover, these materials include a significant proportion of thiolactones. The electrochemical reduction of these thiolacetones is difficult to reverse and this limits the performance of generators (cells) having electrodes made from these materials, such as those of the type Li--(CS.sub.y).sub.n.
Study of the sulphuration of carbon chains by the present inventors has led to the conclusion that it is possible to fix sulphur at temperatures substantially less than those used hitherto and to develop a family of polycarbon sulphide compounds having a new structure.